In History classes, we regularly talk about the cost of various items. The cost of voyages to the United States, the price of an enslaved person, the price of everyday necessities, or the price of war, for example.
Converting money is difficult for a number of reasons. First, “money” is so extremely subjective and relative. There is nothing “natural” and nothing that “makes sense” that says “x” should cost “y.” It is all a social construction based on always-changing social mores and notions of supply and demand. Likewise, money is also difficult to covert over time because the price of items fluctuates as technology improves or social pressure sets in. Powerful companies like Walmart can drive prices down (and up!) with bully tactics.
Additionally, the “thing” that money is based on is always changing. There are/have been economies and monies based on gold or silver or other equally constructed “notions.” Economies have been based on trade – especially when people didn’t/don’t need money per se. Most recently we have the bitcoins.
“Money” as we think of it in the United States only really began in the Civil War era with the National Currency Acts of 1863 and 1865. Capitalism, likewise, largely started during the Second Industrial Revolution that followed and continued to through 1920s.
Money is also difficult to convert because of how it relates and does not relate to the overall condition of the economy and currencies in other countries.
In sum, like all of history, money is not logical. It is not suppose to make sense.
Nonetheless, I have found a really good website for working toward an understanding of money and its relative values overtime. This website is MEASURING WORTH. This website takes the above into account and shows the results in tables.
One document I use in History classes is “Sale of Slaves and Stock.” This is an advertisement for an auction which occurred on Monday, September 22, 1852, in Savannah, Georgia. Thirty-six enslaved individuals were sold at this auction with a cumulative price of $30,755.00 (USD 1852). In 2013, that amount of money would equal approximately $957,000.00 (USD 2013). The data is broken down further:
The website has several useful essays that explain their methodology and what all of the different numbers mean. (Not being an economist, I have not fully processed all of this.) These can be found here. If anyone understands the details of economics and has time to provide a simple explanation for all of this other data, please let me know. For now, I understand that for purpose of having a direct impression for how much $10 would equal in various times the “consumer price index” is the best one to use.